Filter devices of this kind are state of the art and are used in a number of different applications and for the filtration of different flow-capable media. Different device designs are conceivable depending on the field of application. Preferred application fields are the cleaning of fluids, such as hydraulic fluids, lubricants or fuels. Such devices can also be used for water treatment or in conjunction with process fluids or working fluids of other kinds. To ensure an uninterrupted operation of the connected system to be supplied with the filtrate, regeneration of the filter elements is essential for realizing the filtration in a consecutive manner by backflushing. During respective backwashing phases, a partial flow of the filtrate flows through the filter element to be regenerated in the opposite direction to remove the dirt from the element and carry it away. To be able to remove stubborn contaminants in the backwashing operation, backwashing operation is known not only to employ the operating pressure or system pressure, but to support the backflushing operation with a pressure control device.
As related prior art, WO 2012/079661 A1 discloses a filter device of the type described above. The pressure control device has a hydropneumatic piston accumulator. The accumulator piston forms the mobile separating element between a gas side and a fluid side, which fluid side is connected to the filtrate side in the filter housing of the filter device. The filter elements are arranged rotatable in the filter housing in such a way that a filter element to be regenerated can be aligned by its raw or clean side with a backflushing outlet, on which a backflushing valve is located. In order to trigger the backflushing operation for this filter element, the backflushing valve is opened, so that for the backflushing operation the volume of the fluid side with the accumulator pressure of the piston accumulator as pressure gradient is available for removing the contaminants.